Association of Microbleeds on Susceptibility-Weighted Imaging with Ferroptosis and Prognosis in Rabbits with Spinal Cord Injury.

BACKGROUND: Susceptibility-weighted imaging (SWI) is a common imaging technique used to identify cerebral microbleeds. Given that spinal cord injury (SCI) often creates an environment that favors ferroptosis, a type of cell death driven by iron, this study aimed to explore the relationship between microbleeds on SWI and ferroptosis, and explore the effect of deferoxamine on SCI. METHODS: Thirty-six rabbits were divided into three groups: sham, SCI, and SCI with deferoxamine (DFO, a ferroptosis inhibitor) treatment (SCI+DFO). Following 48 hours of SCI modeling, the rabbits underwent magnetic resonance imaging (MRI) and SWI examinations. Ferroptosis markers and spinal cord tissue morphology were examined, and the modified Tarlov's score was used to assess neurological function. RESULTS: SWI analysis revealed that rabbits in the SCI group exhibited lower signal intensities and larger microbleed areas compared to the those in the SCI+DFO group (p < 0.05). The SCI+DFO group demonstrated significantly decreased iron and malondialdehyde (MDA) levels, coupled with increased glutathione (GSH) and glutathione peroxidase 4 (GPX4) levels, along with attenuated ferroptosis (p < 0.05). This group also displayed greater Neuronal Nuclei (NeuN) expression, Tarlov's scores, and neurological recovery rates (all p < 0.05). A significant positive correlation was found between the microbleed area and iron content (r = 0.59, p = 0.04), MDA (r = 0.75, p = 0.01), and mitochondrial damage (r = 0.90, p < 0.01). Conversely, a negative correlation was established between the microbleed area and GPX4 levels (r = -0.87, p < 0.01), as well as neurological function recovery (r = -0.62, p = 0.03). CONCLUSION: The extent of microbleeds on SWI following SCI is closely correlated with ferroptosis, and the inhibition of ferroptosis could improve neurologic function. These findings suggest that the area of microbleeds on SWI could potentially serve as a predictive marker for ferroptosis in spinal cord injury.

Changes in neurological and pathological outcomes in a modified rat spinal cord injury model with closed canal.

Most animal spinal cord injury models involve a laminectomy, such as the weight drop model or the transection model. However, in clinical practice, many patients undergo spinal cord injury while maintaining a relatively complete spinal canal. Thus, open spinal cord injury models often do not simulate real injuries, and few previous studies have investigated whether having a closed spinal canal after a primary spinal cord injury may influence secondary processes. Therefore, we aimed to assess the differences in neurological dysfunction and pathological changes between rat spinal cord injury models with closed and open spinal canals. Sprague-Dawley rats were randomly divided into three groups. In the sham group, the tunnel was expanded only, without inserting a screw into the spinal canal. In the spinal cord injury with open canal group, a screw was inserted into the spinal canal to cause spinal cord injury for 5 minutes, and then the screw was pulled out, leaving a hole in the vertebral plate. In the spinal cord injury with closed canal group, after inserting a screw into the spinal canal for 5 minutes, the screw was pulled out by approximately 1.5 mm and the flat end of the screw remained in the hole in the vertebral plate so that the spinal canal remained closed; this group was the modified model, which used a screw both to compress the spinal cord and to seal the spinal canal. At 7 days post-operation, the Basso-Beattie-Bresnahan scale was used to measure changes in neurological outcomes. Hematoxylin-eosin staining was used to assess histopathology. To evaluate the degree of local secondary hypoxia, immunohistochemical staining and western blot assays were applied to detect the expression of hypoxia-inducible factor 1α (HIF-1α) and vascular endothelial growth factor (VEGF). Compared with the spinal cord injury with open canal group, in the closed canal group the Basso-Beattie-Bresnahan scores were lower, cell morphology was more irregular, the percentage of morphologically normal neurons was lower, the percentages of HIF-1α- and VEGF-immunoreactive cells were higher, and HIF-1α and VEGF protein expression was also higher. In conclusion, we successfully established a rat spinal cord injury model with closed canal. This model could result in more serious neurological dysfunction and histopathological changes than in open canal models. All experimental procedures were approved by the Institutional Animal Care Committee of Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, China (approval No. HKDL201810) on January 30, 2018.

Aldehyde dehydrogenase 2 overexpression inhibits neuronal apoptosis after spinal cord ischemia/reperfusion injury.

Aldehyde dehydrogenase 2 (ALDH2) is an important factor in inhibiting oxidative stress and has been shown to protect against renal ischemia/reperfusion injury. Therefore, we hypothesized that ALDH2 could reduce spinal cord ischemia/reperfusion injury. Spinal cord ischemia/reperfusion injury was induced in rats using the modified Zivin's method of clamping the abdominal aorta. After successful model establishment, the agonist group was administered a daily consumption of 2.5% alcohol. At 7 days post-surgery, the Basso, Beattie, and Bresnahan score significantly increased in the agonist group compared with the spinal cord ischemia/reperfusion injury group. ALDH2 expression also significantly increased and the number of apoptotic cells significantly decreased in the agonist group than in the spinal cord ischemia/reperfusion injury group. Correlation analysis revealed that ALDH2 expression negatively correlated with the percentage of TUNEL-positive cells (r = -0.485, P < 0.01). In summary, increased ALDH2 expression protected the rat spinal cord against ischemia/reperfusion injury by inhibiting apoptosis.